Marihuana and mood in human volunteers

Fifteen adult male marihuana smokers volunteered to live on a hospital research ward for a 31-day study which included a five-day baseline, a 21-day marihuana smoking period and a concluding five-day baseline. Subjects rated their moods and level of intoxication each day at scheduled occasions. Analyses of variance indicated a significant trend in the mood ratings which increased slightly in the euphoric direction just before smoking marihuana (compared to routine ratings) and further increased slightly after smoking marihuana. Level of intoxication ratings and mood ratings were not significantly correlated, but an intoxicated subject's mood ratings were significantly correlated with the average mood ratings of other subjects intoxicated or not. The results suggest that marihuana may increase a person's susceptibility to the moods of others and the feeling of being in harmony with others may be a positive reinforcer.